Implantable active medical devices, such as cardiac rhythm management devices (pacemakers and defibrillators) and a variety of implantable muscle/nerve stimulators, for example, generally include a battery and battery-powered electronic pulse generator contained within a hermetically sealed housing or case and attached to a lead connector housing or block. The hermetically sealed housing most often comprises one or more device shields (also known as shields) and may include a header plate all hermetically joined to form a hermetic cavity. The lead connector block (may also be known as connector header) is often affixed to the hermetically sealed housing with brackets, metal solder, laser or resistance welding, pins, screws, fasteners and/or a medical grade adhesive. The method of fixation requires extensive design and load testing to ensure adequate fixation. The function of the lead connector block is to electrically and mechanically couple the electronic pulse generator with the therapy lead. The lead connector block is typically attached to the exterior of the hermetically sealed housing and is significant to defining the overall device shape and volume. Most often with each new device design, a new lead connector block must also be designed requiring substantial project resources and project schedule.
The electronics within the hermetically sealed housing are conductively coupled to the lead connector block via an electrical feedthrough assembly. Electrical feedthroughs serve the purpose of providing a conductive path extending between the interior of a hermetically sealed container and a point outside the hermetically sealed housing that ultimately connects to the electrical contacts that interface with the therapy lead connector rings. The conductive path through the feedthrough usually includes a conductor pin or terminal that is electrically insulated from the hermetically sealed housing and hermetically bonded to a feedthrough housing or ferrule. The feedthrough housing is hermetically assembled to the device housing most often by laser welding. While this arrangement has proven to be highly reliable, it involves a variety of expensive manufacturing processes and parts that necessarily increase the cost and overall volume of the resulting product and limit device shape or configuration.
Ongoing efforts by the industry to reduce the size of the implantable device are desired. Early implantable pacemakers back in the 1960's were about the size of a hockey puck. With advances in microelectronics and integrated circuitry, significantly more features and capabilities have been embodied in implantable active medical devices that can be very small. Nonetheless, efforts to further reduce the size of implantable active medical devices continue in the industry.